1. Field of the Invention
The present invention relates to a disk cartridge including a write protect mechanism for one disk having a recording capacity that is different from a recording capacity of another disk but having an identical external form to that of the other disk, with a write protect mechanism for the other disk having the different recording capacity held at a write disable state.
2. Description of the Related Art
Hitherto, a disk cartridge includes a disk-shaped recording medium such as an optical disk and a magneto-optical disk rotatably accommodated within a cartridge body thereof and includes a write protect member provided on one side of the cartridge body for preventing improper writing and/or erasing of data to and/from the disk-shaped recording medium. FIGS. 21 to 23B show a write protect mechanism of a disk cartridge 10 called mini disk (MD) as that kind of disk cartridge. Here, FIG. 21 is an exploded perspective view of a part of the disk cartridge 10 where a write protect member 101 is attached. FIGS. 22A and 22B are internal plan views of a lower half 103 where the write protect member 101 is at a write enable position. FIGS. 23A and 23B are internal plan views of the lower half 103 where the write protect member 101 is at a write disable position.
The write protect member 101 is a molded product made of a synthetic resin material such as polypropylene and is assembled in a storage section 104 at one corner of the lower half 103. The storage section 104 includes a write enable/disable detecting hole 105 into which a write protect detecting plug of a writer/reader side enters for detecting whether writing to the disk-shaped recording medium is enabled or disabled. In the storage section 104, the write protect member 101 is operated to selectively move to a write enable position that closes the write enable/disable detecting hole 105 or a write disable position that opens the write enable/disable detecting hole 105 through an operation guiding hole 106 provided by butting an upper half 102 and the lower half 103 against each other.
A writer/reader determines that the recording medium is write-enabled if the write protect detecting plug of the writer/reader entered into the write enable/disable detecting hole 105 is restricted by the write protect member 101. On the other hand, the writer/reader determines that the recording medium is write-disabled when the write protect detecting plug can enter into the write enable/disable detecting hole 105 without restriction.
As shown in FIGS. 22B and 23B, the mini disk cartridge 10 has a spare hole 107 adjacent to the write enable/disable detecting hole 105. The spare hole 107 has a circular opening part of a substantially equal diameter to that of the write enable/disable detecting hole 105.
In recent years, increases in recording density and recording capacity of a disk-shaped recording medium have been demanded. For example, for the disk cartridge 10 mainly for music application, a disk cartridge having a disk-shaped recording medium with a recording capacity high enough for writing video data of moving images, for example, and writers/readers therefor have been developed. Like an existing disk cartridge having a low recording capacity, the disk cartridge having a high recording capacity includes a write protect member for protecting the disk-shaped recording medium from improper writing and/or erasing thereto and/or therefrom. Furthermore, for the convenience of use, a writer/reader compliant thereto has been also developed which has a function of reading from an existing disk cartridge having a low recording capacity.
Documents of related art of the invention are:                JP-A-63-184953 and        JP-A-9-245460        
However, a disk cartridge having a high recording capacity and the disk cartridge 10 having a low recording capacity largely differ in track density and so on. Thus, even when a writer/reader compliant with a disk cartridge having a low recording capacity tries to write data to a disk cartridge having a high recording capacity, proper writing cannot be performed since the width of the magnetic head of the recorder/writer is wide across multiple tracks.
Especially, when a writing operation is improperly performed on a disk cartridge having a high recording capacity with the disk cartridge installed to a writer/reader compliant with a disk cartridge having a low recording capacity, an operation of a magnetic head and optical head may be come unstable, which may cause a failure in the recorder/writer, or the operation is stopped with the magnet head or optical head facing toward the disk surface, which may prevent the ejection of the cartridge, since the disk recording surfaces differ in specification and construction.